1. Field of the Invention
The present invention relates to a video searching/browsing, in particular to a hierarchical hybrid shot change detection method for MPEG-compressed video.
2. Description of the Prior Art
Recently, with the development of a digital video processing technology and an image/video recognition technology, users can search and browse a desired part of a desired video (drama, movie, documentary etc.) at a desired time point.
A shot segmentation technology and a shot clustering technology are basic technologies for performing a non-linear video browsing and a searching Recent researches are concentrated on the shot segmentation technology, while researches about the shot clustering technology start now.
The shot segmentation technology is a technology for dividing video into each separated shot, and the shot clustering technology is a technology for extracting scene information on the basis of time/image/motion/audio/meaning similarity.
The shot means a sequence of video frames gotten from a camera without interruption and it is the most basic unit for analyzing or constructing video data. The video is constructed with lots of shots.
In general, in a video stream, shots are connected by using various editing effects, herein, an editing method used in a video editing is divided into an abrupt shot transition and a gradual shot transition.
The abrupt shot transition is a method for simply connecting the last frame of one shot to the first frame of the other shot without any additional editing effect. Herein, the abrupt shot transition is called as a hard cut.
The gradual shot transition is a method for gradually changing shots from one shot to the other shot by using the editing effect such as a fade, a dissolve, a wipe etc.
In the meantime, among methods for detecting a shot transition region in the video, a shot segmentation method using a global color distribution on the basis of a color histogram is largely used. The shot segmentation method can get color histogram information after decoding video frames up to a picture level prescribed by a MPEG, accordingly its processing speed is very slow.
In order to solve above-mentioned problem, there is a shot segmentation method using a characteristic of a MPEG stream in compressed domain and a characteristic of picture types of I, P, B. And also there is a shot change detection method using type information of a macro block corresponding to position of adjacent B pictures in a MPEG stream and a comparison table of themselves.
However, when a plurality of shot change candidates are detected in a GOP (group of Pictures), it is difficult to accurately detect an actual shot change point with the shot segmentation method, and its performance is low.
In the meantime, in the shot change detection algorithm method, because shot change detection is performed in the compressed domain, its processing speed is very fast. However, if a shot change candidate region is big, the shot change detection can be easily affected by the performance of an encoder because all processing are performed in the compressed domain. And its actual processing speed or detection performance are low because miss ratio and false alarm ratio are high. Accordingly it is not suitable for an actual application.